1. Technical Field
The present invention relates to a resin composition for a printed circuit board, an insulating film, a prepreg, and a printed circuit board.
2. Description of the Related Art
As electronic devices have advanced and complicated functions have been required, a printed circuit board has gradually been light, thin, and miniaturized. In order to satisfy these demands, a wiring of a printed circuit has become more complicated, highly densified, and multi-functionalized. In addition, in the printed circuit board, as a buildup layer becomes multi-layered, fineness and high density of the wiring has been demanded. Electric, thermal, and mechanical properties required in the board as described above are important factors.
The printed circuit board is configured of copper mainly serving as circuit wiring and a polymer serving as an interlayer insulating material. In the polymer configuring an insulating layer as compared with copper, various properties, such as a coefficient of thermal expansion, a glass transition temperature, thickness-uniformity, and the like, are required. Particularly, the insulating layer should be manufactured so as to have a thin thickness.
As the circuit board has been thin, rigidity of the board itself has been lowered, such that a defect may be generated by a warpage phenomenon at the time of mounting components at a high temperature. In this case, a thermal expansion property and a heat resistance property of thermosetting polymer resin act as important factors. At the time of thermosetting, a structure of the polymer, a network between polymer resin chains configuring a composition for a board, and a cure density closely affect the heat expansion property and the heat resistance property.
Meanwhile, an epoxy resin composition including a liquid crystal oligomer has been disclosed in Patent Document 1. However, a network between a curing agent and a polymer resin was not sufficiently formed, such that a coefficient of thermal expansion was not sufficiently lowered so as to be suitable for a printed circuit board, and a glass transition temperature was not sufficiently raised.